Pressure-filling is a way to fill bottles, cans, or other containers with a liquid filling material under counter-pressure. Examples of counter-pressure include clamping pressure and filling pressure.
Known pressure-filling methods have in common a multiphase filling process. In a preparation phase, the container presses against the filling element to form a seal. An inert gas, such as carbon dioxide gas, then pre-pressurizes the container's interior to the counter-pressure. A subsequent filling phase includes filling the container with the liquid filling material under counter-pressure. During a relief phase that follows, the pressure within the container is relieved to ambient pressure. This pressure-relief is preferably performed in stages. A first stage involves relieving the pressure to a pre-relief pressure that is above ambient pressure. The second stage takes the pressure the rest of the way to ambient pressure.
Usually, the filling process features still further treatment phases. For example, there may also be an evacuation phase in which the container's interior is evacuated. There may be a rinsing phase, in which the container's interior is rinsed with inert gas. In some cases, there are several alternating, successive evacuation and rinsing phases. The individual treatment phases can themselves have several partial phases. For example, the filling phase can have partial phases for slow priming, for fast filling, for slow residual filling, for steadying the filling material, etc.
In known methods and filling systems, the initiation and termination of essential treatment phases is time-controlled. In these cases, treatment durations for individual treatment phases are saved in a computerized controller of the filling system. This data can be saved in a product-specific manner and/or a container-specific manner.
Treatment durations for individual treatment phases are usually obtained from experience. These durations take into account the switching times required for opening and closing the valves that control the treatment media during the treatment phases. One disadvantage of this is that the actual sequence of the treatment phases is not monitored and the knowledge of appropriate treatment durations depends heavily on the experience of the particular operating staff. Even the smallest lack of attention and/or inaccuracy can lead to either a reduction in the quality of the filled product, an increase in the consumption of inert gas, or both.
A known method for pressure-filling containers includes monitoring and/or diagnosing individual filling elements during the filling process to detect a malfunction of the filling elements early and to initiate countermeasures. This requires a separate pressure sensor at each filling element for measuring the pressure profile.
Such a method also aims to optimize the duration of the relief phase upon completion of the actual filling process. This includes providing a pressure sensor at a filling element to measure the profile of the container's internal pressure during the relief phase and for defining the duration of the relief phase for all filling elements of the filling system.